. The Street railway journal . appeals very stronglyto the mechanical engineer. There hasbeen no skimping in amount of material,and all material has been put where it willdo good. Fig. 6 shows the detail of the windingof the field shown as a whole in Fig. 5. Thelaminated poles with slots for ventilation,the compact and substantial field coils andthe solid bridges, which hold them in place,are here excellently shown. These cuts ofthe large polyphase generators readily ex-plain the ease with which high voltages canbe generated directly from stationary arma-tures. With machines of the revolving p
. The Street railway journal . appeals very stronglyto the mechanical engineer. There hasbeen no skimping in amount of material,and all material has been put where it willdo good. Fig. 6 shows the detail of the windingof the field shown as a whole in Fig. 5. Thelaminated poles with slots for ventilation,the compact and substantial field coils andthe solid bridges, which hold them in place,are here excellently shown. These cuts ofthe large polyphase generators readily ex-plain the ease with which high voltages canbe generated directly from stationary arma-tures. With machines of the revolving pole form it is easyto get sufficient space for well-insulated coils, and questionsof the overlapping at the ends of armature coils having greatdifference of potential are eliminated, since in the absenceof centrifugal stress and in the presence of ample room atthe ends of the armature, the coils can be kept extremelywell clear of one another. The efficiencies of the largepolyphase machines that have already been mentioned are. FIGS. 4 AND 5.—STATOR AND ROTOR OF 7SO-KW, SLOW SPEED, THREE-PHASE GENERATOR into the armature slots. These Coils, like all coils of mod-ern machines, are wound on forms, thoroughly insulated,and slipped into place. The general design of the arma-ture frame shows the same device of a circular truss, whichhas already been referred to, and the engraving gives avery impressive idea of its size. The revolving field of this particular machine is shownin Fig- 5> which is particularly instructive as showing thecare taken in the ventilation of the laminated poles and theextremely ingenious and useful method of locking the fieldcoils into place by heavy, cast, bridge pieces, which spanthe space from pole to pole and secure the coils in the very high, and as a whole their performance is exceedinglysatisfactory in every respect. In building plants using direct-connected units of sogreat output as those to which reference has been madeit becomes necessary to dea
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Keywords: ., bookcentury1800, bookdecade1880, bookidstreetrailwa, bookyear1884
